Buildbot makes heavy use of Twisted Python's support for services - software
modules that can be started and stopped dynamically. Buildbot adds the ability
to reconfigure such services, too - see Reconfiguration.
Twisted arranges services into trees; the following section describes the
service tree on a running master.

The hierarchy begins with the master, a buildbot.master.BuildMaster
instance. Most other services contain a reference to this object in their
master attribute, and in general the appropriate way to access other
objects or services is to begin with self.master and navigate from there.

The master has several child services:

master.metrics

A buildbot.process.metrics.MetricLogObserver instance that
handles tracking and reporting on master metrics.

msater.caches

A buildbot.process.caches.CacheManager instance that provides
access to object caches.

master.pbmanager

A buildbot.pbmanager.PBManager instance that handles incoming
PB connections, potentially on multiple ports, and dispatching those
connections to appropriate components based on the supplied username.

master.change_svc

A buildbot.changes.manager.ChangeManager instance that manages
the active change sources, as well as the stream of changes received from
those sources. All active change sources are child services of this instance.

master.botmaster

A buildbot.process.botmaster.BotMaster instance that manages
all of the slaves and builders as child services.

The botmaster acts as the parent service for a
buildbot.process.botmaster.BuildRequestDistributor instance (at
master.botmaster.brd) as well as all active slaves
(buildbot.buildslave.AbstractBuildSlave instances) and builders
(buildbot.process.builder.Builder instances).

master.scheduler_manager

A buildbot.schedulers.manager.SchedulerManager instance that
manages the active schedulers. All active schedulers are child services of
this instance.

master.user_manager

A buildbot.process.users.manager.UserManagerManager instance
that manages access to users. All active user managers are child services
of this instance.